The present invention relates generally to optical devices and more particularly to fiber optic packages and methods for assembling the same.
Optical packages and assemblies, particularly those with single mode fiber couplings, generally require careful placement of components within the package to ensure proper alignment between the optical fiber and the various optical components including the optical source, to ensure a sufficient amount of light entering the optical fiber. Fiber optic packages with single mode fiber couplings are typically assembled to meet sizing and alignment tolerances, some on the order of tenths of a micron. Generally, active alignment techniques are required to meet such tight alignment tolerances. In active alignment, a light emitting device such as a laser is active, i.e., emitting light, when the other optical components are positioned and re-positioned with respect to the light emitting device. A sensing or receiving element must be monitored and the components may be re-positioned based on the sensed/received light. Active alignment techniques therefore require considerable time and manpower. Active alignment is used to align the light emitting source to the other optical components to form an optical subassembly (OSA) and also to align the light emitting device and the OSA to the optical fiber or other optical transmission or receiving medium. Depending on the application and number of functions of the package, multiple active alignment steps may be required to produce a package of an OSA coupled to an optical transmission medium.
Passive alignment techniques, in contrast, involve the placement and alignment of optical components without the active emitting device emitting light. For passive alignment, mechanical guides and the like may be used or the components may simply be affixed to pre-determined positions. The passive alignment process is much simpler, quicker and less work-intensive, but the tradeoff is that poorer alignment is achieved and tight alignment tolerances generally are not achieved using conventional techniques.
It would therefore be desirable to align optical components using passive alignment techniques while satisfying the tight alignment tolerances required in today's optoelectronics industry.